The present invention relates to a distance measuring device for a camera and the like, and more particularly to an active-type distance measuring device for a camera.
A variety of active-type distance measuring devices have been conventionally proposed. In these distance measuring devices, a light projecting circuit operates a predetermined number of times (or for a predetermined period of time), and then an optical signal from the object is amplified and its voltage integrated and converted in an A/D manner to thereby calculate the distance to the object.
However, a plurality of comparators for converting the voltage across the terminals of an integrating capacitor into a digital signal are required in such a distance measuring device, as described, for example, in Japanese Patent Application Laid-Open No. 3-119307. In addition, since the resolution is in proportion to the number of such comparators, if the distance measuring precision is to be enhanced, the circuit would have to be enlarged and would become more complicated and expensive.